1. Field of the Invention
The present invention relates to a resist pattern slimming treatment method of performing a slimming treatment on a resist pattern formed on a substrate, in a semiconductor process or the like.
2. Description of the Related Art
With increased miniaturization of semiconductor devices, it has become more difficult to secure a sufficient exposure contrast of a fine pattern having a ratio between the line width and the space width being 1:1 only by using optical exposure technology. Hence, a technique of forming a fine pattern by combining a new layer to a pattern or a technique of forming a fine pattern by performing the pattern formation in two steps has been discussed. However, it is important in any of the techniques how to form a reduced line width of the pattern. Examples of a slimming treatment method that is a method of the treatment in which a series of photolithography composed of resist coating, heat treatment, exposure processing and developing treatment is performed to form a resist pattern on a substrate, and then the line width of the formed resist pattern is reduced (hereinafter, referred to as a “slimming treatment”), include the following ones.
There is a method in which a resist pattern is formed using a chemically amplified resist, and then an acid coating is applied on the resist pattern so that a surface layer of the resist pattern changes to be alkali-soluble, and the surface layer changed to be alkali-soluble is removed, whereby the line width of the resist pattern is made smaller than the line width that has been formed first (see, for example, Japanese Patent Application Laid-open No. 2001-281886).
There is another method in which a resist pattern is formed using a chemically amplified resist, then a modifying material containing acid is applied onto the resist pattern and diffused into the resist pattern, and thereafter the modifying material and a portion of the resist pattern which has been made soluble by diffusion of the modifying material are removed, whereby the line width of the resist pattern is made smaller than the line width that has been formed first (see, for example, Japanese Patent Application Laid-open No. 2002-299202).
There is still another method in which a resist pattern is formed, then a pattern thinning material (shrinking material) is applied onto the resist pattern to form a pattern mixing layer on the front surface of the resist pattern, and thereafter the thinning material and the pattern mixing layer are removed, whereby the line width of the resist pattern is made smaller than the line width that has been formed first (see, for example, Japanese Patent Application Laid-open No. 2003-215814).